TreeSet要实现对象的排序，该对象要实现Comparable 接口compareTO方法
public class Book implements Comparable {
public int id;
public String name;
public double price;
public String press;
@Override
public int compareTo(Object o) {
Book book=(Book)o;
int val=this.id-book.id; 先通过id比较 id是数字可以直接做差
if(val==0) { 如果id相同然后比较名字
val=this.name.compareTo(book.name);
}
return val;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public String getPress() {
return press;
}
public void setPress(String press) {
this.press = press;
}
public Book(int id, String name, double price, String press) {
super();
this.id = id;
this.name = name;
this.price = price;
this.press = press;
}
@Override
public String toString() {
return "Book [id=" + id + ", name=" + name + ", price=" + price + ", press=" + press + "]";
}
public Book() {
super();
// TODO Auto-generated constructor stub
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + id;
result = prime * result + ((name == null) ? 0 : name.hashCode());
result = prime * result + ((press == null) ? 0 : press.hashCode());
long temp;
temp = Double.doubleToLongBits(price);
result = prime * result + (int) (temp ^ (temp >>> 32));
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Book other = (Book) obj;
if (id != other.id)
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
if (press == null) {
if (other.press != null)
return false;
} else if (!press.equals(other.press))
return false;
if (Double.doubleToLongBits(price) != Double.doubleToLongBits(other.price))
return false;
return true;
}
public void setBook(Book book) {
this.book=book;
}
public int getBook() {
// TODO Auto-generated method stub
return 0;
}